Method of straightening and testing tubular elements



May 5, 1959 A. P. HELDENBRAND 2,884,986

METHOD OF STRAIGHTENING AND TESTING TUBULAR ELEMENTS Filed April 28, 1954 INVENTOR. A. P. HE L DE NBPAND WMMW ATTORNEY METHOD OF STRAIGHTENENG AND TESTING TUBULAR ELEMENTS Arthur P. Heldenbrand, Oklahoma City, Okla.

Application April 28, 1954, Serial No. 426,138

1 Claim. (Cl. 153-35) This invention relates to improvements in methods of and apparatus for straightening, testing, and strengthening tubular elements, such as oil well drill pipe, oil well tubing and the like. The instant application is a continuation-inpart of my co-pending application entitled Means for, and a Process of Straightening, Testing and Grading Well Pump Rods and Tubing, filed March 8, 1954, Serial No. 414,614, and now abandoned.

As it is Well known in the oil industry, drill pipe and well tubing frequently becomes bent, both through transportation and use. Heretofore, it has been the practice to straighten such elements by holding the elements and applying a force transversely to the crooked portion. In straightening an element by this method, theelement is frequently weakened at various points along its length and is rendered potentially dangerous for future use. Furthermore, the threads at each end of the pipe or tubing are frequently formed slightly out of alignment with the longitudinal axis of the pipe. When such a pipe is straightened by the prior methods, the threads are not aligned with the remainder of the pipe. Therefore, when another joint of drill pipe or tubing is attached thereto, the joints will not be in alignment. In addition, no provision is ordinarily made for testing the strength of the straightened drill pipe or tubing, nor the alignment of the threads. As a result, the operating condition of the straightened pipe or tubing is not discovered until it has been run into an oil well and actually placed in operation.

The present invention contemplates a novel method of straightening, testing and strengthening an entire joint of drill pipe, tubing or the like, wherein the pipe or tubing is, in effect, stressed to approximately its minimum tensile strength. The stressing or pulling is accomplished by grasping the opposite ends of the element through the medium of its threads. Therefore, when the element is placed in tension, the threads will be aligned with the longitudinal axis of the element simultaneously with the straightening operation. Furthermore, the threads will be tested for shearing strength, and the overall length of a drill pipe or tubing joint will be tested for tensile strength. By placing a length of drill pipe or tubing under tension to approximately or slightly above its minimum tensile strength, the granular structure is stress aligned to provide an end product having an increased and uniform strength throughout the length thereof. It will be apparent to those skilled in the art that such a method is particularly adapted for tubular elements having substantial strength in the threaded portions, such as drill pipe, upset tubing and the like.

An important object of this invention is to provide a method of straightening and testing drill pipe and the like, wherein the drill pipe is placed under tension through the medium of the threads at each end thereof.

Another object of this invention is to align the threads at each end of a drill pipe or the like simultaneously with the straightening of the drill pipe.

A further object of this invention is to re-align the gran- United States Patent ice ular structure of a metallic tubular element to straighten and strengthen the element.

A still further object of this invention is to simultaneously straighten, test, and strengthen crooked or bent drill pipe and the like in one operation. I

Another object of this invention is to provide an economical and simple method of straightening, testing and strengthening drill pipe and the like.

Other objects and advantages of this invention will be evident from the following detailed description, when taken in conjunction with the accompanying drawings, which illustrate my invention.

In the drawings:

Figure 1 is a plan view, partially schematic, of the necessary mechanism for carrying out my invention.

Figure 2 is a sectional view taken along lines 2-2 of Fig. 1.

Figure 3 is an enlarged view taken along the lines 3--3 of Fig. 1.

Figure 4 is another enlarged sectional view taken along lines 44 of Fig. 1.

Referring to the drawings in detail, and particularly Figs. 1 and 2, reference character 4 generally designates a straightening and testing machine comprising a pair of parallel and horizontally disposed support members 6 and 8, preferably formed from angle iron as illustrated. A plurality of support legs 10 are rigidly attached to the members 6 and 8 to support the machine 4 at the desired height. And a plurality of braces 11 (only one of which is shown) are secured to the members 6 and 8 in spaced relation along the length of the machine 4 to retain the support members in the desired parallelrelationship. A transverse retaining plate 12 is rigidly secured to the ends 14 and 16 of the members 6 and 8 for purposes as will be herinafter set forth.

Hydraulic cylinders 18 are rigidly secured to each of the support members 6 and 8 in a parallel relationship. Each cylinder 18 is provided with a plunger 19 (see Fig. 2) reciprocally disposed therein, and each plunger 19 has a plunger or piston rod 20 which extends outwardly from the end of the respective cylinder 18 in a direction away from the retaining plate 12. Another retaining plate 22 is rigidly secured to the outer ends of the plunger rods 20 for purposes as will be hereinafter set forth.

A hydraulic pump and control unit, schematically illustrated at 24, is supported on the member 6 to supply fluid under pressure through a conduit 26 to the ends of the cylinders 18 opposite the plunger rods 20. The pump unit 24 (and associated mechanism) is preferably of the type shown in my co-pending application entitled Automatic Hydraulic Pressure Release Device, filed February 1, 1954, Serial No. 407,481, to supply hydraulic fluid under pressure to the cylinders 18 until the resistance to the pressure is slightly reduced. Springs 28 are interconnected to support members 6 and 8 and the retaining plate 22 to constantly urge the plungers 19 and rods 20 inwardly in the cylinders 18.

The crooked drill pipe or the like 30 is secured to the retaining plates 12 and 22 by threaded pull pins 32 and 34. As shown in Fig. 3, the pull pin 32 comprises a cylindrical body member 36 of a size to extend through an aperture 38 formed in the central portion of the retaining plate 12. The inner end 40 of the body 36 is counterbored and threaded at 50 to receive the male threaded end 52 of the drill pipe 30. A circumferential flange 54 extends outwardly from the central portion of the body 36 to abut the outer face 56 of the retaining plate 12 around the aperture 38. Suitable V-braces 58 are preferably secured to the body 36 outwardly of the flange 54 to prevent bending of the flange 54 outwardly over the outer end of the pin 32.

The pull pin 34 (see Fig. 4) is also provided with a 3 "cylindrical'body'portionfifl-of a size to extend through an aperture62 formed in'the central portion of the retaining plate 22. The apertures 62 and 38 are formed in alignment on an axis parallel with the cylinders 18 to assure a true straighteningof the drill pipe '30 as will be'hereinafter set forth. The inner end 64 of thebody=60 isare'duced in diameter-and-threacled to receive the female threaded end 66-of'the drillpipe 30. Ac'ircumferential flange 68 is'also provided around the central-portion of the pin 34 to 'abut the outer-face 70 of the retaining plate 22 around the aperture 62. SuitableV-braces 72 are-preferably secured to'the body 60 to prevent bendingof'the flange '68 when a pull is exerted on the inner end6'4 of the body 60.

*In constructing the machine '4, the retaining plates 12 and '22 are secured at'right angles tothe-axis of the cylinders 18, and, as previously-'noted,-the apertures 38 and 62 are formed in alignment. Furthermore,'the inner faces of the pull pin flanges '54 and 68, and the mating outer faces 56 and 70 of the'retaining plates 12 and 22 respectively, are preferably-rnachinedto provide a c'losefit and position the pull pins 32 and 34 in alignment.

Operation :In30peration oftthemachine 4, the crooked drill pipe 30 is placed between the support members 6 and 8, as illustrated in Fig. .1, and isthen secured to the pull pins 32 and34. The pull :pins 32 and.34 are threaded tightly on the respective ends of the drill pipe 30. The pumping unit '24 is then placed in operation to supply fluid into the cylinders 18 and expand :or expel the plunger rods 20 outwardlyfrom the cylinders 18 in a uniform manner. It will be observed that the pressure conduit v26 will supply an equal amount of:fiuid.to each of the cylinders 18 to move the piston rods 20-an equal distance and with an equal force.

As the plunger rods 20 and retaining plate 22 are moved .ina direction away from the retaining plate 12, the pull pin .flanges;54iand-68 will contact the retaining plates 12 and 22 respectively, and the drill pipe 30 will be placed under tension. The resulting tension will stress align the entire length of the .drill pipe 30. Simultaneously, the threaded engagementof the pull pins 32 and 34 with the opposite ends of the drill pipe 30 will test the shear strength of the drill pipe threads andalign the threads with the longitudinal axis of the drill pipe.

'When a sufiicient .forceis applied to bring the-drill pipe 30to.its yield point, the plunger 19 will begin'to move'in the cylinders 18 at a faster rate. Whereupon, the pumpingunit 24 will cease to operate and release=the hydraulic pressure in the cylinders 18. In placing the drill pipe 30 under tension to. its yield point, or slightly beyond its minimum yield point, the pipe30 is adequately tested for tensile strength. It the pipe 30 has the desired tensile strength, .itbecomesstress aligned to provide an increased and uniformstrengththroughout'the entire length thereof. .Ifthe pipe .30 is below a specified tensile strength,'the pipe will be'slightly stretched to actuate the unit 24 and=release the hydraulic pressure in the cylinders 18 at a pressure (asindicated by the unit '24) below the pressure required stancesthe pipe will be parted.

When the drill pipe 30 has been straightened, the pull pins 32 and 34 are unthreaded and the pipe 30 removed from the machine 4. Whereupon, the springs 28 will retract the plunger rods 20 into the cylinders 18 and the machine will be ready for a subsequent straightening operation.

From the foregoing, itis apparent that the present invention provides'a novel method of straightening and testing drillpipe and the like, wherein the drill pipe is placed under tension through the medium of the threads at each end thereof. The threads of the drill pipe are aligned with the longitudinal axis of the drill pipe simultaneously with the straightening operation, and the entire length of the drill pipe joint is stress aligned to assure uniform strength throughout. The present method is economical and simple to perform.

Changes made be madein the combination'and arrange ments of stepsand operations as heretofore setforthinthe specification and shownin the drawings, it being understood that any modification in the precise embodiment of the invention'may'be made within the scope of the following claim without departing from the spirit'of theinvention.

I claim: In amethod of straightening crooked pipe and thelike 'havingthreaded'ends, which consists of threading a pull 'pin onto each end of the pipe over substantially the entire length of the threaded area of the respective end of the pipe, forcing said pull pins in opposite directions along a common axis with a force at least as great as the minimum tensile strength of 'the pipe at atmospheric temperature while allowing universal pivotal movement of the pins whereby the axis of the threaded ends may be brought into axial alignment with said common axis during such application offorce to straighten the entire length of the pipe.

References Cited in the file of this patent UNITED STATES PATENTS 478,454 Murphy July 5, 1892 523,633 Glenhill July 24, 1894 1,033,623 Schiller July 23, 1912 1,122,289 Loveland Dec. 29, 1914 1,341,431 Morrow May 25, 1920 1,367,099 Schmidt 'Feb. 1, 1921 2,075,968 Von Heydekampf Apr. 6, 1937 2,136,538 Borwick Nov. 15, 1938 2,336,524 Bannister Dec. 14, 1943 2,757,536 Heldenbrand Aug. 7, 1956 FOREIGN PATENTS 291,425 Italy Nov. 26, 1929 OTHER REFERENCES 'A.S;T.M. Standards, Part '1 (Farms Metals), pages 1238 and 1239. 

